Application of Laser Scattering on Detection of Subsurface Damage in Silicon Wafers

Abstract

Silicon is widely used in semiconductor industry. Over 90% of all semiconductor devices are manufactured upon silicon substrates (wafers). Many manufacturing processes are needed for the wafer preparation. In order to ensure high quality silicon wafers, the damaged layer induced by each manufacturing process must be reduced or eliminated by its subsequent processes. So, it is critical to assess subsurface damage (SSD). As a nondestructive measurement method, laser scattering is preliminarily applied to measure SSD in silicon wafers. Optical transmission properties of silicon wafer are measured first to make sure that silicon wafers have the appropriate optical transmission properties for laser scattering. Photomicrographs and scatter images are obtained on sample wafers with different depth of subsurface damage. The correlation between photomicrographs and scatter images is discussed. The results from this study show that laser scattering can potentially be applied to measure subsurface damage across whole silicon wafers.